BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
Stenostoma leucops O. Scumrpr. 
Stenostoma leucops O. Scumipt, 1848, p. 59; SiLLIMAN, 1885, p. 55; Orr, 1892. 
Stenostoma neoboracense GIRARD, 1898, p. 220. 
Said to have been abundant in the aquaria of the laboratory during May, 
1896, Of this species I received only some stained mounted specimens. The 
following account is from notes made by Dr. Kofoid upon living material. 
When extended, in motion, the worms measured 1 to 14 mm. in length. 
Margins transparent, central portion brownish, posterior third of the animal 
often with a faint tinge of pink or maroon, and in one specimen this color 
extended throughout the length of the animal. Several lobe-like projections 
on the surface near the mouth when the animal is contracted. The anterior 
end, when extended, exhibits two lateral depressions, —the ciliated pits. 
The projecting anterior end is very mobile, and from its activity undoubtedly 
highly sensitive. No trace of sexual organs. Cilia very prominent on the 
general surface of the body, and always directed forward when the animal 
is quiescent, Locomotion is sometimes in a posterior direction, and is ac- 
companied by waves of constriction progressing from in front backwards. 
Forward motion, however, is apparently due wholly to ciliary action. Repro- 
duction by fission was indicated in some specimens by the existence of well 
marked constrictions at about one third the total length from the posterior end ; 
the constriction involved both the hypodermis and the digestive tract. 
